As the friction drive carriage-type conveying apparatus having the above configuration, as described in Patent Document 1, for example, there has been known a conveying apparatus configured such that a plurality of load bar units located in series along a moving direction are connected horizontally bendable about vertical joint axes to constitute a friction drive load bar, and a conveyed object support base is supported by one of the plurality of load bar units, for example, a central load bar positioned in the center in the longitudinal direction of the friction drive load bar, and trolleys which support both ends in the longitudinal direction of the friction drive load bar and positions of joint axes in between are supported on a guide rail laid along the moving path side so as to be capable of traveling, and the friction drive load bar is friction-driven by a friction drive wheel of a friction drive means arranged on the moving path, whereupon the conveyed object support base is moved along the moving path. In the conveying apparatus described in Patent Document 1, the conveying carriage is composed of the conveyed object support base, the central load bar unit supporting the conveyed object support base, and front and rear two trolleys supporting the central load bar unit. Meanwhile, as shown in Patent Document 2, there has been also known a friction drive carriage-type conveying apparatus configured by attaching one of the load bar units (for example, the central load bar unit) of the friction drive load bar as described in Patent Document 1 to one of left and right lateral side portions of the conveying carriage having wheels.
Patent Document 1: Japanese Published Unexamined Patent Application No. H07-33009
Patent Document 2: Japanese Published Unexamined Patent Application No. 2003-191839
In the well-known friction drive carriage-type conveying apparatuses described in Patent Documents 1 and 2, a horizontally bendable friction drive load bar having a joint axis at an intermediate position in the longitudinal direction is used. Therefore, as compared with a friction drive method of sandwiching the conveying carriage itself by a friction drive wheel and back-up roller of a friction drive means, there is no need to enhance the strength of the conveying carriage for friction drive. Further, such an effect can be obtained that the moving direction of the conveying carriage can be changed by providing a horizontal curved path section in the moving path without turning the moving direction of the conveying carriage through the use of a turntable. However, when a conveying traveling body composed of the friction drive load bar and the conveying carriage travels in the closest state of adjoining front and rear conveying traveling bodies thereof, it is necessary for conveyed objects (for example, automobile vehicle bodies) loaded on corresponding conveying carriages to be configured so as not to interfere with each other by making the entire length of the conveying traveling body longer than the entire length of the conveyed object loaded on the conveying carriage. Therefore, when work floor surface portions projecting forward and rearward from the conveyed object are intended to be secured at both front and rear end portions of the conveying carriage, the entire length of the conveying carriage needs to be made substantially as long as the entire length of the friction drive load bar.
As a result, a long and heavyweight integral conveying carriage is required. Coupled with the need to configure the conveying carriage such that the conveying carriage having been divided for truck transportation can be assembled at an installation site, costs of the conveying carriage are significantly increased. In addition, on the occasion when the friction drive load bar having a bendable joint structure in relation to the horizontal direction is friction-driven along the horizontal curved path section, both front and rear end portions of the conveying carriage protruding forward and rearward from both front and rear ends of the load bar units attached to the conveying carriage project greatly outward from a center line of the horizontal curved path section along which the friction drive load bar moves while being bent. As a result, a floor area necessary for the moving path of the conveying carriage at the horizontal curved path section becomes remarkably large.